iMac - iMac G5 fan noise - is it excessive?

In the morning when I wake my iMac up, a fan starts up in it (which I totally expect). But the quality of the noise is what concerns me. It's not simply a whooshy or whirry noise, there is a brittle plastic component to it as well, as if just the very tip of a fan blade were rubbing up against something. It's only very mildly annoying, and stops after the first couple minutes of operation.

But my concern is whether this may, in the long run, lead to premature failure of the fan and subsequently shorten the lifespan of a machine I am otherwise truly in love with (there, I said it.)

First of all, this sounds unfortunate. The iMac sits literally inches from your ears, and so this continual sound would be very annoying. Secondly, it sounds like a problem. You should never hear mechanical rubbing type noises from a properly functioning fan.

I guess the history would be of interest here as well. Is this a new development, or has the iMac always done this? If it is new, definitely have it checked out. You are right in your assumption that a degraded or improperly functioning fan could lead to a premature end of lifespan for your iMac. Cooling is key in computers and I would guess that a fan that is rubbing against its housing isn't operating as efficiently as it should, hence the heat inside the case may be higher than planned.

If I were you, I would have it looked at anyway, just to remove the annoyance factor. I HATE noise from my computers. Quiet computing has become a real passion of mine.

This is a brand new iMac, just out of the box. So far as I know, it has always done this.

I'm reticent to ship the mac away for warranty service however (as it is the only computer in the house, and I am unfortunately in the process of using it for my current job search). Is it a component that could be easily replaced at home?

I had tried resetting the SMC (System Management Controller), deleting the Cache folder, eliminating startup items, all to no avail. Then I got a brush for cleaning the keyboard and dusted the bottom grill of my iMac g5 and saw a moderate amount of dust fall out. Within a minute the fan went virtually silent.